diff --git a/maven-model-builder/src/main/java/org/apache/maven/model/building/DefaultModelBuilder.java b/maven-model-builder/src/main/java/org/apache/maven/model/building/DefaultModelBuilder.java
index 065f2c8c7d23..a9b9399209bd 100644
--- a/maven-model-builder/src/main/java/org/apache/maven/model/building/DefaultModelBuilder.java
+++ b/maven-model-builder/src/main/java/org/apache/maven/model/building/DefaultModelBuilder.java
@@ -58,6 +58,7 @@
 import org.apache.maven.model.building.ModelProblem.Version;
 import org.apache.maven.model.composition.DependencyManagementImporter;
 import org.apache.maven.model.inheritance.InheritanceAssembler;
+import org.apache.maven.model.interpolation.AbstractStringBasedModelInterpolator;
 import org.apache.maven.model.interpolation.ModelInterpolator;
 import org.apache.maven.model.io.ModelParseException;
 import org.apache.maven.model.management.DependencyManagementInjector;
@@ -288,7 +289,6 @@ protected ModelBuildingResult build(ModelBuildingRequest request, Collection<Str
         Collection<String> parentIds = new LinkedHashSet<>();
         List<ModelData> lineage = new ArrayList<>();
 
-        // Models built to resolve a dependency (a dependency POM, one of its parents, or an
         // Models resolved for dependency, parent or BOM POMs evaluate only platform-derived
         // activation (JDK, OS, activeByDefault).
         boolean externalModel = isExternalModelBuildingRequest(request);
@@ -509,10 +509,13 @@ void performFor(String value, String locationKey, Consumer<String> mutator) {
      * rather than a POM belonging to the project being built. Such requests use
      * {@link ModelBuildingRequest#VALIDATION_LEVEL_MINIMAL}, see for instance
      * {@code DefaultArtifactDescriptorReader#loadPom}; a project build uses
-     * {@link ModelBuildingRequest#VALIDATION_LEVEL_MAVEN_2_0} or higher.
+     * {@link ModelBuildingRequest#VALIDATION_LEVEL_MAVEN_2_0} or higher. A request that sets
+     * {@value AbstractStringBasedModelInterpolator#FULL_EXTERNAL_INTERPOLATION_PROPERTY} is never external, so
+     * that tools building their own projects at a low validation level can opt out.
      */
     private static boolean isExternalModelBuildingRequest(ModelBuildingRequest request) {
-        return request.getValidationLevel() < ModelBuildingRequest.VALIDATION_LEVEL_MAVEN_2_0;
+        return request.getValidationLevel() < ModelBuildingRequest.VALIDATION_LEVEL_MAVEN_2_0
+                && !AbstractStringBasedModelInterpolator.isFullExternalModelBuild(request);
     }
 
     /**
diff --git a/maven-model-builder/src/main/java/org/apache/maven/model/interpolation/AbstractStringBasedModelInterpolator.java b/maven-model-builder/src/main/java/org/apache/maven/model/interpolation/AbstractStringBasedModelInterpolator.java
index 41399878eb8f..45037908716c 100644
--- a/maven-model-builder/src/main/java/org/apache/maven/model/interpolation/AbstractStringBasedModelInterpolator.java
+++ b/maven-model-builder/src/main/java/org/apache/maven/model/interpolation/AbstractStringBasedModelInterpolator.java
@@ -235,8 +235,20 @@ public Object getValue(String expression) {
 
     private static boolean restrictExternalModelInterpolation(ModelBuildingRequest config) {
         return config.getValidationLevel() < ModelBuildingRequest.VALIDATION_LEVEL_MAVEN_2_0
-                && !Boolean.parseBoolean(config.getSystemProperties().getProperty(FULL_EXTERNAL_INTERPOLATION_PROPERTY))
-                && !Boolean.parseBoolean(config.getUserProperties().getProperty(FULL_EXTERNAL_INTERPOLATION_PROPERTY));
+                && !isFullExternalModelBuild(config);
+    }
+
+    /**
+     * Tells whether {@value #FULL_EXTERNAL_INTERPOLATION_PROPERTY} is set, as a system or a user property,
+     * which exempts models built below {@link ModelBuildingRequest#VALIDATION_LEVEL_MAVEN_2_0} from the
+     * restrictions that apply to models resolved from a repository.
+     *
+     * @param config the model building request
+     * @return {@code true} if the property is set to {@code true}
+     */
+    public static boolean isFullExternalModelBuild(ModelBuildingRequest config) {
+        return Boolean.parseBoolean(config.getSystemProperties().getProperty(FULL_EXTERNAL_INTERPOLATION_PROPERTY))
+                || Boolean.parseBoolean(config.getUserProperties().getProperty(FULL_EXTERNAL_INTERPOLATION_PROPERTY));
     }
 
     private static ValueSource restrictToSafeExpressions(ValueSource source) {
diff --git a/maven-model-builder/src/test/java/org/apache/maven/model/building/ResolvedDependencyProfileActivationTest.java b/maven-model-builder/src/test/java/org/apache/maven/model/building/ResolvedDependencyProfileActivationTest.java
index ab6d38ca2006..faa53153ed86 100644
--- a/maven-model-builder/src/test/java/org/apache/maven/model/building/ResolvedDependencyProfileActivationTest.java
+++ b/maven-model-builder/src/test/java/org/apache/maven/model/building/ResolvedDependencyProfileActivationTest.java
@@ -21,6 +21,7 @@
 import java.util.Properties;
 
 import org.apache.maven.model.Model;
+import org.apache.maven.model.interpolation.AbstractStringBasedModelInterpolator;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -237,6 +238,33 @@ void testExternalModelUserPropertyActivationIsSuppressed() throws Exception {
                 "user-property profile must NOT fire in external model build (consumer -D suppressed)");
     }
 
+    @Test
+    void testFullExternalInterpolationEvaluatesAllActivators() throws Exception {
+        // maven.model.dependencyInterpolation.full opts a MINIMAL build out of the external
+        // restrictions, for tools that build their own projects at that validation level (#13347).
+        Properties up = userPropertiesWithTestValues();
+        up.setProperty(AbstractStringBasedModelInterpolator.FULL_EXTERNAL_INTERPOLATION_PROPERTY, "true");
+        Model model = build(ModelBuildingRequest.VALIDATION_LEVEL_MINIMAL, systemPropertiesWithTestValues(), up);
+
+        assertEquals("activated", model.getProperties().get("profile.file"), "file profile must fire");
+        assertEquals(
+                "activated", model.getProperties().get("profile.user.property"), "user-property profile must fire");
+        assertEquals(
+                "activated", model.getProperties().get("profile.sys.property"), "system-property profile must fire");
+        assertNull(
+                model.getProperties().get("profile.pom.property"), "POM-declared-property profile must still NOT fire");
+    }
+
+    @Test
+    void testFullExternalInterpolationAsSystemPropertyEvaluatesUserPropertyProfile() throws Exception {
+        Properties sp = systemPropertiesWithTestValues();
+        sp.setProperty(AbstractStringBasedModelInterpolator.FULL_EXTERNAL_INTERPOLATION_PROPERTY, "true");
+        Model model = build(ModelBuildingRequest.VALIDATION_LEVEL_MINIMAL, sp, userPropertiesWithTestValues());
+
+        assertEquals(
+                "activated", model.getProperties().get("profile.user.property"), "user-property profile must fire");
+    }
+
     @Test
     void testExternalModelSystemPropertyActivationIsPreserved() throws Exception {
         // System properties are platform facts and must drive activation even in external builds.